METHOD AND APPARATUS FOR MANUFACTURING A PLASTIC FUEL TANK COMPRISING A BUILT IN-NECK

Description

[0001] The present invention relates to a method for manufacturing a plastic fuel tank comprising a built-in neck; to apparatus for implementing the said method and to a petrol tank resulting from this method/apparatus and using the built-in neck for attaching its filler pipe, a spout or a flange.

[0002] Fuel tanks on board vehicles of various kinds generally have to meet imperviousness and permeability standards in relation to the type of use for which they are designed and the environmental requirements that they have to satisfy. Both in Europe and throughout the world we are currently experiencing a considerable tightening of the requirements concerned with limiting the emissions of pollutants into the atmosphere and into the environment in general. The design of fuel tanks is therefore evolving quickly towards techniques capable of better guaranteeing the imperviousness and safety under varying conditions of use. Furthermore, attempts are also being made to minimize the losses originating from the pipes and various accessories connected to the tanks. For example, the attaching of pipes and, in particular, of the filler pipe, spouts and flanges to the tank may present problems of permeability. With a view to reducing these problems, various solutions are proposed, most of which call upon an intermediate part or neck. Flowever, problems of imperviousness may still arise at this neck.

[0003] Hence, patent application US2002130515 proposes a method for directly incorporating a neck into the tank during the blowing of the latter. However, this solution leads to a neck the wall thickness of which is not constant, something which is not ideal for impervious coupling and, furthermore, may lead to problems of impact strength and additional materials costs (it being necessary to have an excess thickness in order for at least the minimum thickness required to be achieved throughout).

[0004] Document DE10010900 discloses a method for manufacturing a plastic fuel tank according to the preamble of claim 1.

[0005] Document DE10010900 also discloses an apparatus suitable for implementing such a method according to the preamble of claim 8.

[0006] It is therefore an object of the invention to provide a method which also allows a neck to be incorporated into a plastic fuel tank at the time of its manufacture by moulding, but does so using a method and apparatus which are such that the wall thickness of the neck is very uniform and therefore makes it possible to avoid the abovementioned problems.

[0007] The problems are solved by a method and an apparatus according to the characterizing portions of claims 1 and 8.

[0008] The term "fuel tank" is intended to denote a sealed tank able to store fuel under diverse and varying environmental and usage conditions. An example of this tank is a tank fitted to motor vehicles.

[0009] The fuel tank according to the invention is made of plastic.

[0010] The term "plastic" denotes any material comprising at least one synthetic resin polymer.

[0011] All types of plastic may be suitable. Particularly suitable plastics come from the thermoplastics category.

[0012] The term "thermoplastic" denotes any thermoplastic polymer, including thermoplastic elastomers, as well as blends thereof. The term "polymer" denotes both hoxnopolymers and copolymers (especially binary or ternary copolymers). Examples of such copolymers are, non-limitingly, random copolymers, linear block copolymers, other block copolymers and graft copolymers.

[0013] Any type of thermoplastic polymer or copolymer whose melting point is below the decomposition temperature is suitable. Synthetic thermoplastic that have a melting range spread over at least 10 degrees Celsius are particularly suitable. Examples of such materials include those that exhibit polydispersion in their molecular weight.

[0014] In particular, polyolefins, thermoplastic polyesters, polyketones, polyamides and copolymers thereof may be used. A blend of polymers or copolymers may also be used, as may a blend of polymer materials with inorganic, organic and/or natural fillers such as, for example, but non-limitingly, carbon, salts and other inorganic derivatives, natural fibres or polymeric fibres. It is also possible to use multilayer structures consisting of stacked layers bonded together comprising at least one of the polymers or copolymers described above.

[0015] One polymer that is often used is polyethylene. Excellent results have been obtained with high density polyethylene (HDPE).

[0016] The wall of the tank may be made up of a single layer of thermoplastic or of two layers. One or more other possible additional layers may, advantageously, consist of layers of a material that forms a barrier to the liquids and/or gases. As a preference, the nature and thickness of the barrier layer are chosen in such a way as to limit as far as possible the permeability towards the liquids and gases in contact with the interior surface of the tank. As a preference, this layer is based on a barrier resin, that is to say on a resin impermeable to the fuel such as EVOH for example (a copolymer of ethylene and partially hydrolysed vinyl acetate). Alternatively, the tank may be subjected to a surface treatment (fluoration or sulphonation) the purpose of which is to render it impermeable to the fuel.

[0017] According to the invention, the tank is produced by moulding a parison. A "parison" is intended to mean a preform, generally extruded, which is intended to constitute the wall of the tank once it has been moulded to the required shape and size. This preform does not necessarily have to be made as a single piece.

[0018] Thus, advantageously, the parison in fact consists of two separate pieces, which may for example be two sheets. However, as a preference, these pieces result from the cutting of one and the same extruded tubular parison as described in application EP 1110697 in the name of the Applicant Company. According to this variant, once a single parison has been extruded it is cut along its entire length, along two diametrically opposed lines, to obtain two separate parts (sheets).

[0019] By comparison with the moulding of two separately extruded sheets, the thickness of which is therefore constant, this approach makes it possible to use parisons of variable thickness (that is to say a thickness that is not constant along their length), obtained by virtue of an appropriate extrusion device (generally an extruder fitted with an adjustable punch die). A parison such as this takes account of the reduction in thickness which occurs during moulding at certain points on the parison, as a result of the non-constant rates of deformation of the material in the mould.

[0020] According to the invention, the parison is deformed locally to mould a neck intended for the attachment of a pipe, a spout or a flange to the tank. As a preference, this is the tank filler pipe which is generally a part of relatively complex geometry, moulded separately from the tank. It may also be a spout for connecting venting lines or fuel lines for instance, or a flange bearing accessories. This neck generally has a substantially cylindrical shape, a wall more or less as thick as that of the tank and a length suited to obtaining a strong mechanical attachment of the pipe that is to be coupled to it. Said neck may bear a thread (for instance for fixation by screwing of a flange bearing a complementary thread).

[0021] The moulding of the neck is performed independently from the moulding of the tank. It may take place before or after the latter moulding operation. For practical reasons, it preferably takes place before the tank is moulded.

[0022] Indeed, certain methods have recourse to the insertion of a core prior to the moulding of the tank for other reasons (for incorporating accessories for example) and this step may then be put to good use for (at least partially) moulding the neck.

[0023] In general, the method according to the invention comprises at least the following steps :

• a parison is introduced into the mould;
• the core is introduced into the mould, inside the parison;
• the mould is closed;
• the parison is pressed firmly against the mould cavity by blowing through the core and/or drawing a vacuum behind the mould;
• the neck is moulded by displacing the form within the counter-form.

[0024] Thus, according to the invention, the moulding of the neck occurs using two complementary pieces : a convex form (or punch) and a concave counter-form both of suitable shape and size that the form can penetrate the counter-form and, in doing so, mould the neck through local compression of the material. These two pieces are secured one to the core and the other to the mould. What that means is that if the counter-form is secured to the core (in the case of a re-entrant neck), then the form is secured to the mould, and vice versa (in the case of a protruding neck). These two pieces are therefore, at a given point in time, able to move one relative to the other because the form has to be able to penetrate the counter-form in order to mould the neck. In general, the movement of one of the two pieces is brought about by a suitable device of the hydraulic ram type. This device is advantageously borne by the core (and so too therefore is the moving piece).

[0025] In the case a neck bearing a thread must be moulded, said thread can be incorporated into the form so that after its moulding, the tank must be taken of the mould by unscrewing said part (neck) from the mould.

[0026] Advantageously, the moulding of the neck is carried out in such a way as to compensate for the reduction in thickness that has a natural tendency to form in the final part of the neck (the end furthest from the parison).

[0027] With the same end result in mind, and still to encourage a constant wall thickness in the vicinity of the neck, the parison is preferably kept under compression around the neck during withdrawal of the form from the counter-form.

[0028] In the method according to the invention, the tank may be moulded by blow-moulding the parison (pressing the parison firmly against the mould using a pressurized fluid (generally air)). In this method, the parison has sometimes already experienced the influence of the pressurized fluid before the neck is blown and/or formed, this being with a view to ensuring that the parison is firmly pressed against the mould. Thus, for example, before blowing and/or moulding the neck, it may prove advantageous to press the parison against the mould by blowing through the core. In consequence, in such an instance, before withdrawing the core from the mould, the mould will need to be degassed in order, in particular, to avoid an excessively sudden expansion of the trapped pressurized fluid, and the accompanying noise.

[0029] Hence, according to a preferred variant, the method according to the invention comprises the following steps :

• a parison is introduced into the mould;
• the core is introduced into the mould, inside the parison;
• the mould is closed;
• the parison is pressed firmly against the mould cavity by blowing through the core and/or drawing a vacuum behind the mould;
• the neck is moulded by displacing the moving piece within the counter-form;
• degassing is performed;
• the mould is opened to withdraw the core;
• the mould is closed again onto the parison and the parison is blown in order to produce the tank;
• the tank is removed from the mould.

[0030] The degassing step may be done in any appropriate way.

[0031] In general, the parison is first of all pierced (for example by puncturing it with a needle) and then the fluid is let out of the mould (for example using a valve).

[0032] Alternatively, the tank may be moulded by thermoforming the parison (i.e. by pressing the parison (= one or two sheet(s) of molten material) firmly against the wall of the thermoforming mould by drawing a vacuum in the volume between the molten material and the wall of the mould).

[0033] Blowing yields good results particularly from the viewpoint of the duration of the manufacturing cycles. For a given manufacturing rate, this method therefore requires a lower investment in machinery (by comparison with thermoforming, whether vacuum thermoforming (as described hereinabove) or compression thermoforming (using a core or punch)).

[0034] Having moulded the tank incorporating the neck, the end of this neck has then to be cut off in order to disengage it. This cutting is done by any appropriate means. As a preference, this cutting is performed using a rotary cutter or any other tool capable of making a cut without generating chips.

[0035] The present invention also relates to apparatus suitable for applying the method described hereinabove.

[0036] As explained above, a thread can be incorporated into the form in order to obtain a neck on which a part (like a flange) bearing a complementary thread can be screwed.

[0037] As a preference, these two elements (form and counter-form) have suitable shape and size that the neck can be compression moulded avoiding the reduction in wall thickness at its end, as mentioned hereinabove.

[0038] Likewise, in order to be able to apply local compression around the neck as the form is being withdrawn, as mentioned hereinabove, the form or the counter-form of this apparatus is preferably secured to a support equipped with at least one spring. This support then advantageously has a shape, size and location which is such that, as the moving piece (generally, the one supported by the core) is being withdrawn, the support is pressed against the parison, around the neck, by the said spring, so as to maintain local compression at that point. The intensity and duration of this compression depend on the rating of the spring. Alternatively or in addition, the function of the spring may be exerted by the blowing pressure.

[0039] Advantageously, especially in the case the neck is intended for fixation of the filler pipe, it is moulded towards the inside of the tank (a so-called re-entrant neck) so as to lie inside the internal volume delimited by the wall of this tank. As far as the apparatus used is concerned this means that the part secured to the core is preferably the counter-form and that therefore the part secured to the mould is the form. One advantage of a re-entrant neck is that the diameter of the external skin is sized throughout the blowing cycle (and/or possibly during the post-blowing/post-cooling cycle). This improves the tolerances on this external skin (which ultimately constitutes the internal surface of the neck) and, by doing so, improves the quality of the weld welding any further components there might be into this neck (for example using a hot filament). In the case of a protruding neck (where the moving piece (the one secured to the core) is the form), sizing is performed only during the forming of this neck by the core and then by the blowing pressure.

[0040] As a preference, the re-entrant neck is substantially cylindrical and exhibits an entry taper, that is to say that the transition between the surface of the tank and that of the cylindrical neck is rounded. As a preference, this rounding has a fillet radius of at least 5 mm, or even 10 mm. This radius does not, however, advantageously exceed 20 mm. It is advantageously larger if there is space available in the vehicle environment, because that improves impact strength. The presence of such an inlet taper makes assembling the parts easier and limits the risk of stress raisers.

[0041] In certain instances it may be advantageous to mould a flange (or other coupling of appropriate geometry) as one piece with the neck, so as to make it easier to couple an external piece to the said neck. Finally, the present invention also relates to a plastic fuel tank that can be obtained by a method or apparatus as described hereinabove. In particular, it relates to such a tank comprising a built-in neck the wall thickness of which is constant to within +/- 0.1 mm (in which case it is said to have a tolerance of 0.1 mm).

[0042] Such a tank advantageously has a filler pipe, a spout or a flange fixed to the said neck. This fixing may be done in any known way. Thus, for example, it may be by mechanical fastening (using a pipe clamp for example, or merely by screwing in the case the neck and the pipe, spout or flange are bearing complementary threads), by welding, etc.

[0043] One particularly suitable means (besides screwing as explained above) is to weld using a coupling comprising a heating filament (that is to say a metal filament which heats up under an electrical effect when a current is passed through it and does so to a sufficient extent that it melts the plastic and produces the weld). As a particular preference, the said coupling and the weld using it are as described in patent US 2003/0168853. In particular, the coupling has a shape that is appropriate in facilitating the coupling of the heating filament to the source of electrical power. Specifically, the precise dimensions (particularly close tolerances) of the neck moulded using the method according to the invention lend themselves particularly well to this method of welding and make it possible to obtain a particularly uniform weld and to do so repeatably.

[0044] The present invention is illustrated non-limitingly by Figures 1 to 3 where identical numerals denote identical elements, namely: a core (1), a moving piece secured to the core (2) and a mould (3).

[0045] The variant illustrated in Figure 1 is the one in which the moving piece (2) secured to the core (1) is the form and in which the counter-form is secured to the mould (3). This is the case of a protruding neck in which the form is in contact with the neck and therefore sizes the neck only during the formation of the neck.

[0046] In the variants illustrated in Figures 2 and 3 on the other hand, the moving piece (2) secured to the core (1) is the counter-form and the form is secured to the mould (3). This is the case of a re-entrant neck and the form remains in contact with the neck, and therefore sizes the latter also during the moulding of the tank.

[0047] In the variant illustrated in Figure 2, when the counter-form is removed from the form via the core, there is global decompression of the material in and around the neck. By contrast, in the variant illustrated in Figure 3, because of the presence of a support (4) equipped with two springs (5), when the counter-form is removed the support remains in contact with the perimeter of the neck for a while longer (until the springs return the said support), making it possible to maintain the compression of the material at this point and, in doing so, to obtain better uniformity of thickness.

[0048] In each of the cases depicted, it is necessary for it to be possible to release the neck from the mould. For that to be possible it is necessary in certain instances to provide an additional moving piece in the mould, this is what is indicated by the second arrow in the figures (the one which does not lead from the moving piece (2) proper).

Claims

1. Method for manufacturing a plastic fuel tank comprising a built-in neck, by moulding a parison in a mould (3), in which method the neck is moulded by locally deforming the parison using a concave counter-form and a convex form able to enter the counter-form, the form and the counter-form being secured one of them to the mould (3) and the other to a core (1) located inside the mould (3), or vice versa, characterized in that the moulding of the neck using the convex form and the concave counter form takes place before or after the moulding of the rest of the fuel tank, a movement of the form or the counter form being brought about by a device borne by the core (1).

2. Method according to the preceding claim, characterized in that the tank is based on HDPE and comprises a layer of a barrier material or has been subjected to a surface treatment in order to render it impermeable to the fuel.

3. Method according to either one of the preceding claims, characterized in that the parison consists of two sheets resulting from the cutting of an extruded tubular parison.

4. Method according to any one of the preceding claims, characterized in that it comprises the following steps :

- a parison is introduced into the mould (3);

- the core (1) is introduced into the mould (3), inside the parison;

- the mould (3) is closed;

- the parison is pressed firmly against the mould cavity (3) by blowing through the core (1) and/or drawing a vacuum behind the mould (3);

- the neck is moulded by displacing the form within the counter-form.

5. Method according to any one of the preceding claims, characterized in that form and counter-form have suitable shape and size so that the neck is compression moulded in order to avoid a reduction in wall thickness at its end.

6. Method according to any one of the preceding claims, characterized in that either the form or the counter form is secured to a support equipped with at least one spring, said support having a shape, size and location such that, as either the form or the counter-form is being withdrawn, the support is pressed against the parison, around the neck.

7. Method according to any one of the preceding claims, characterized in that the tank is blow-moulded or thermoformed.

8. Apparatus suitable for implementing the method according to the preceding claims and comprising a mould (3) and a core (1) situated inside the mould (3), the mould (3) and the core (1) being equipped one with a concave counter-form and the other with a convex form which is able to penetrate the counter-form in order to mould a neck, characterized in that the apparatus comprises a device borne by the core (1) and in that either the form or the counter-form is a moving piece (2) secured to the core (1), a movement of the moving piece (2) being brought about by the device, such that the moulding of the neck using the convex form and the concave counter form can take place before or after the moulding of the rest of the fuel tank.

9. Apparatus according to the preceding claim, characterized in that either the form or the counter-form is secured to a support equipped with at least one spring.

10. Apparatus according to Claim 8 or 9, characterized in that the form is secured to the mould (3) and the counter-form is secured to the core (1).

11. Method according to any one of claims 1 to 7, characterized in that a filler pipe, a spout or a flange is fixed to the neck by screwing or by welding using a heating filament incorporated into a welding coupling.

Ansprüche

1. Verfahren zur Herstellung eines Kraftstofftanks mit eingebautem Stutzen, durch Gießen eines Vorformlings in eine Gießform (3), wobei bei dem Verfahren der Stutzen durch lokale Verformung des Vorformlings unter Verwendung einer konkaven Gegenform und einer konvexen Form, die in der Lage ist, in die Gegenform einzutreten, gegossen wird, wobei eine von der Form und der Gegenform an der Gießform (3) befestigt ist, und die andere an einem Kern (1), der innerhalb der Gießform (3) angeordnet ist, oder umgekehrt, dadurch gekennzeichnet, dass das Gießen des Stutzens unter Verwendung der konvexen Form und der konkaven Form vor oder nach dem Gießen des Rests des Kraftstofftanks erfolgt, wobei eine Bewegung der Form oder der Gegenform durch eine von dem Kern (1) getragene Vorrichtung herbeigeführt wird.

2. Verfahren nach dem vorangehenden Anspruch, dadurch gekennzeichnet, dass der Tank auf HDPE (Polyethylen hoher Dichte) aufbaut und eine Schicht aus einem Barrierenmaterial aufweist oder einer Oberflächenbehandlung unterzogen wurde, um diese kraftstoffundurchlässig zu machen.

3. Verfahren nach einem der vorangehenden Ansprüche, dadurch gekennzeichnet, dass der Vorformling aus zwei Platten besteht, die das Ergebnis des Schneidens eines extrudierten rohrförmigen Vorformlings sind.

4. Verfahren nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass es die folgenden Schritte aufweist:

- Ein Vorformling wird in die Gießform (3) eingeführt;

- der Kern (1) wird in die Gießform (3) innerhalb des Vorformlings eingeführt;

- die Gießform (3) wird geschlossen;

- der Vorformling wird mittels Blasen durch den Kern (1) und/oder Ziehen eines Vakuums hinter der Gießform (3) fest gegen das Formnest (3) gepresst;

- der Stutzen wird durch Verlagerung der Form innerhalb der Gegenform gegossen.

5. Verfahren nach einem der vorangehenden Ansprüche, dadurch gekennzeichnet, dass Form und Gegenform eine geeignete Form und Größe aufweisen, so dass der Stutzen formgepresst wird, um eine Verringerung der Wanddicke an seinem Ende zu vermeiden.

6. Verfahren nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass entweder die Form oder die Gegenform an einem mit mindestens einer Feder ausgerüsteten Träger befestigt ist, wobei der Träger eine Form, Größe und Positionierung aufweist, die derart ist, dass dann, wenn entweder die Form oder die Gegenform zurückgezogen wird, der Träger gegen den Vorformling um den Stutzen herum gepresst wird.

7. Verfahren nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass der Tank blasgeformt oder thermogeformt wird.

8. Apparat, der zur Durchführung des Verfahrens nach den vorhergehenden Ansprüchen geeignet ist, und eine Gießform (3) und einen innerhalb der Gießform (3) angeordneten Kern (1) aufweist, wobei von der Gießform (3) und dem Kern (1) eine(r) mit einer konkaven Gegenform und die/der andere mit einer konvexen Form ausgerüstet ist, die zum Eindringen in die Gegenform in der Lage ist, um einen Stutzen auszubilden, dadurch gekennzeichnet, dass der Apparat eine von dem Kern (1) getragene Vorrichtung aufweist, und dass entweder die Form oder die Gegenform ein sich bewegendes Teil (2) ist, das an dem Kern (1) befestigt ist, wobei eine Bewegung des sich bewegenden Teils (2) von der Vorrichtung herbeigeführt wird, so dass das Gießen des Stutzens unter Verwendung der konvexen Form und der konkaven Gegenform vor oder nach dem Gießen des Rests des Kraftstofftanks erfolgen kann.

9. Apparat nach dem vorangehenden Anspruch, dadurch gekennzeichnet, dass entweder die Form oder die Gegenform an einem mit mindestens einer Feder ausgerüsteten Träger befestigt ist.

10. Apparat nach Anspruch 8 oder 9, dadurch gekennzeichnet, dass die Form an der Gießform (3) befestigt, und die Gegenform an dem Kern (1) befestigt ist.

11. Verfahren nach einem der Ansprüche 1 bis 7, dadurch gekennzeichnet, dass ein Einfüllstutzen, ein Ausguss oder ein Flansch an dem Stutzen durch Schrauben oder durch Schweißen unter Verwendung eines in eine Schweißmuffe integrierten Heizdrahtes befestigt wird.

Revendications

1. Procédé pour la fabrication d'un réservoir à carburant en matière plastique comprenant une goulotte intégrée, par moulage d'une paraison dans un moule (3) , dans lequel on moule la goulotte par déformation de la paraison au moyen d'une contre forme concave et d'une forme convexe apte à pénétrer dans la contre forme, la forme et la contre forme étant solidaires l'une du moule (3) et l'autre, d'un noyau (1) situé à l'intérieur du moule, ou vice versa, caractérisé en ce que le moulage de la goulotte utilisant la forme convexe et la contre forme concave a lieu avant ou après le moulage du restant du réservoir, un mouvement de la forme ou de la contre forme étant provoqué par un dispositif porté par le noyau (1).

2. Procédé selon la revendication précédente, caractérisé en ce que le réservoir est à base de PEHD et comprend une couche en matériau barrière ou a été soumis à un traitement de surface en vue de le rendre imperméable au carburant.

3. Procédé selon l'une quelconque des revendications précédentes, caractérisé en ce que la paraison est constituée de 2 feuilles issues de la découpe d'une paraison tubulaire extrudée.

4. Procédé selon l'une quelconque des revendications précédentes, caractérisé en ce qu'il comprend les étapes suivantes :

- on introduit une paraison dans le moule (3);

- on introduit le noyau (1) dans le moule (3), à l'intérieur de la paraison ;

- on ferme le moule (3);

- on plaque la paraison sur l'empreinte du moule (3) par soufflage au travers du noyau (1) et/ou aspiration sous vide derrière le moule (3);

- on procède au moulage de la goulotte par déplacement de la forme à l'intérieur de la contre forme.

5. Procédé selon l'une quelconque des revendications précédentes, caractérisé en ce que la forme et la contre forme ont une forme et une dimension adéquates pour provoquer le moulage par compression de la goulotte de sorte à éviter une réduction d'épaisseur de paroi à son extrémité.

6. Procédé selon l'une quelconque des revendications précédentes, caractérisé en ce que soit la forme, soit la contre forme est solidaire d'un support muni d'au moins un ressort, ce support ayant une forme, des dimensions et un emplacement tels que lors du retrait de la forme ou de la contre forme, le support est poussé contre la paraison, autour de la goulotte.

7. Procédé selon l'une quelconque des revendications précédentes, caractérisé en ce que le réservoir est moulé par soufflage ou thermoformage.

8. Appareillage convenant pour la mise en oeuvre du procédé selon les revendications précédentes et comprenant un moule (3) et un noyau (1) situé à l'intérieur du moule, le moule (3) et le noyau (1) étant l'un muni d'une contre forme concave et l'autre, d'une forme convexe apte à pénétrer dans la contre forme pour mouler une goulotte, caractérisé en ce que l'appareil comprend un dispositif porté par le noyau (1) et en ce que soit la forme, soit la contre forme est une pièce mobile (2) solidaire du noyau (1), un mouvement de la pièce mobile (2) étant provoqué par le dispositif de sorte que le moulage de la goulotte utilisant la forme convexe et la contre forme concave peut avoir lieu avant ou après le moulage du restant du réservoir.

9. Appareillage selon la revendication précédente, caractérisé en ce que soit la forme, soit la contre forme est solidaire d'un support muni d'au moins un ressort.

10. Appareillage selon la revendication 8 ou 9, caractérisé en ce que la forme est solidaire du moule (3) et la contre forme est solidaire du noyau (1).

11. Procédé selon l'une quelconque des revendications 1 à 7, caractérisé en ce que une tubulure de remplissage, un collet ou une bride est fixé à la goulotte par vissage ou par une soudure au moyen d'un filament chauffant intégré à un raccord de soudure.

Drawing